Sputter target, barrier film and electronic component

ABSTRACT

A sputter target is made of a Ti—Al alloy containing Al in the range of 1 to 30 atm %. In the Ti—Al alloy constituting the sputter target, Al exists in at least one of a solid solution state in Ti and a state in which Al forms an intermetallic compound with Ti, and variation in Al content in the entire target is limited within 10%. Furthermore, an average crystal grain diameter of the Ti—Al alloy is 500 μm or less, and variation in crystal grain diameter in the entire target is limited within 30%. A Ti—Al—N film as a barrier film is formed by using the sputter target made of the Ti—Al alloy as described above. An electronic component includes a barrier film formed on a semiconductor substrate.

TECHNICAL FIELD

The present invention relates to a sputter target suitable for forming abarrier material for a semiconductor substrate or the like and to abarrier film and an electronic component using the same.

BACKGROUND ART

A storage device using a ferroelectric thin film as a storage medium,namely, a so-called ferroelectric memory (FRAM), has recently been underactive development. The ferroelectric memory, which is nonvolatile, hassuch a characteristic that storage capacity thereof is not lost evenafter power source is cut off. Furthermore, spontaneous polarizationinversion is very rapid if the film thickness of the ferroelectric thinfilm is sufficiently small, so that a rapid write and read comparable toDRAM can be realized. Since a memory cell of one bit can be constitutedby a single transistor and a single ferroelectric capacitor, theferroelectric memory is also suitable for mass storage.

As a ferroelectric material, lead zirconate titanate (a solid solutionof PbZrO₃ and PbTiO₃ (PZT)) having a perovskite structure is mainlyused. PZT, however, has such a disadvantage that its major component Pbis likely to be diffused and vaporized at a relatively low temperature(approximately 500° C.), even though having such characteristics of ahigh Curie temperature (approximately 300° C.) and large spontaneouspolarization, and therefore, it is said to be difficult for PZT to copewith miniaturization. Barium titanate (BaTiO₃ (BTO)) is known as atypical ferroelectric material besides PZT. BTO, however has such adisadvantage that remanent polarization thereof is greatlytemperature-dependent due to small remanent polarization and a low Curietemperature (approximately 120° C.) compared with PZT.

It has been found out, however, that BTO, when epitaxially grown on aPt/MgO(100) substrate, allows a BTO film having a film thickness of, forexample, 60 nm to exhibit the Curie temperature of 200° C. or higher.Moreover, it has been confirmed that, when barium strontium titanate(Ba_(a)Sr_(1-a)TiO₃ (BSTO)) is epitaxially grown on a lower electrodemade of Pt and strontium ruthenate (SrRuO₃ (SRO)), ferroelectricityappears in a composition region (a≦0.7) which is not expected to exhibitthe ferroelectricity by nature. This is because a lattice of a BSTOcrystal in a C-axis direction is extended.

Since a ferroelectric Curie temperature shifts to a higher temperatureside in such a BSTO film of a Ba rich, large remanent polarization isobtainable in a room temperature zone, and sufficiently large remanentpolarization can be retained even when the temperature is increased upto approximately 85° C. Consequently, a ferroelectric film suitable forthe storage medium of FRAM can be realized. Meanwhile, the use of BSTOof an Sr rich can realize a thin-film capacitor whose dielectricconstant reaches several times (for example, 800 or higher) as that of acapacitor made of a polycrystalline film. Such a dielectric property issuitable for DRAM.

The practical availability of semiconductor memories such as FRAM andDRAM is expected through the use of the thin-film capacitor having theepitaxially grown BTO film and BSTO film as described above. In puttingthese into practical use, it is necessary to combine a semiconductorsubstrate on which a switching transistor is formed and a memory cellusing a perovskite oxide film (thin-film capacitor). At this time, aproblem exists that the diffusion of elements such as Pt, Ru, Sr, andBa, which constitute the lower electrode and the dielectric thin film ofthe thin-film capacitor, into the transistor has an adverse effect on aswitching operation.

Under the circumstances, a barrier film which prevents mutual diffusionneeds to be formed between the thin-film capacitor and the semiconductorsubstrate. Further, the barrier film itself needs to be epitaxiallygrown on the semiconductor substrate in order to obtain theabove-described epitaxial effect. The use of a titaium nitride (TiN)film and a film made of Ti_(1-x)Al_(x)N(Ti—Al—N) which is a solidsolution of TiN and aluminum nitride (AlN) has been studied as such abarrier film.

TiN, which is superior in a barrier property against Al and the like, isalso utilized as a barrier metal in generally-used Si devices. It isalso excellent in thermal stability since it is a chemical compoundwhose melting point is high (3000° C. or higher), and has a very lowspecific resistance, approximately 50 μΩ·cm in a polycrystalline filmand approximately 18 μΩ·cm in an epitaxial film, which results in anadvantage that contact resistance can be lowered in utilizing anelectric property in the thickness-wise direction.

When TiN is used as the barrier film of the thin-film capacitor,however, oxygen is diffused onto the TiN film, for example, due toannealing at a high temperature (for example, 600° C. or higher)conducted in an element production process for controllingcrystallization of the ferroelectric film so that nitrogen (N) in TiN issubstituted by oxygen (O) to form an oxide film, namely, TiO₂. The lowerelectrode made of Pt, SRO, and so on becomes inferior in adherence dueto volume expansion thereof based on TiO₂ generated on the surface ofthe TiN film and due to the generation of N₂ gas. This results in aproblem that peeling occurs in the lower electrode.

When Al is added to TiN to form the Ti_(1-x)Al_(x)N(Ti—Al—N) film,oxidation resistance can be enhanced. The Ti—Al—N film is formed byreactive sputtering in an atmosphere of argon (Ar) and nitride (N),using a Ti_(1-x)Al_(x) alloy (a Ti—Al alloy) target. Concerning theTi—Al alloy target, for example, Japanese Patent Laid-open ApplicationNo. Hei 6-322530 specifies a Ti—Al alloy target constituted only of adiffusion reaction layer of high-purity Ti and high-purity Al.

Further, aiming at enhancing abrasion resistance and oxidationresistance of cutting tools, sliding components, and so on, JapanesePatent Laid-open Application No. Hei 8-134635 specifies a Ti—Al alloytarget material with a relative density of 99.0 to 100% and free of anycontinuous defect from the surface to the bottom surface thereof.Japanese Patent Laid-open Application No. 2000-100755 specifies a Ti—Alalloy target for forming a barrier film of a semiconductor device, whoseO content is in the range of 15 to 900 ppm.

Further, Japanese Patent Laid-open Application No. 2000-273623 specifiesa Ti—Al alloy target, in which an Al content is 5 to 65 wt %, a radioactive element such as U and Th is 0.001 ppm or lower, an alkali metalsuch as Na and K is 0.1 ppm or lower, Fe which is a transition metal is10.0 ppm or lower, Ni is 5.0 ppm or lower, Co is 2.0 ppm or lower, Cr is2.0 ppm or lower, and purity thereof including impurities is 99.995% orhigher, and Japanese Patent Laid-open Application No. 2000-328242specifies a Ti—Al alloy target containing 15 to 40 atm % or 55 to 70 atm% of Al and having a metal structure with an area ratio of a Ti₃Alintermetallic compound being 30% or higher, and in which the number ofdefects with a diameter of 0.1 mm or larger is 10/100 cm² or less. Thus,various kinds of Ti—Al alloy targets have been developed.

The Ti—Al—N film which is formed by reactive-sputtering the conventionalTi—Al alloy target, however, is inferior in an epitaxial growth propertyon an Si substrate, which results in a problem of hindering theepitaxial growth of the BTO film and the BSTO film. In FRAM using such aBTO film or a BSTO film, a ferroelectric property such as remanentpolarization is not sufficiently obtainable to lower the property andproduction yields of FRAM. When they are applied to DRAM, the propertyand production yields thereof are similarly lowered as well.

Further, when the Ti—Al—N film is formed by reactive-sputtering theconventional Ti—Al alloy target, sudden generation of huge dust islikely to occur while the film is formed by sputtering, which results ina problem of lowering the production yields of FRAM and DRAM. Such aproblem is caused not only when the Ti—Al—N film is used as the barrierfilm of the thin-film capacitor but also when the Ti—Al—N film is usedas the barrier film of a generally-used semiconductor element.

As described above, though the Ti—Al—N-film has a characteristic ofbeing excellent in oxidation resistance by nature, it cannot benecessarily said that sufficient studies have been made on thecomposition, nature, and so on of the Ti_(1-x)Al_(x) alloy target usedfor the formation thereof. This is why such problems occur that theepitaxial growth property of the Ti—Al—N film on the Si substrate isdegraded and in addition, the sudden generation of the huge dust iscaused.

An object of the present invention is to provide a sputter targetenabling the formation of a Ti—Al—N film excellent in the property andquality as a barrier film with good reproducibility. More specifically,an object of the present invention is to provide a sputter targetenabling the epitaxial growth of the Ti—Al—N film with goodreproducibility, and a sputter target enabling the reduction in the dustgeneration. Another object is to provide, through the use of such asputter target, a barrier film and an electronic component whoseproperty, quality and production yields are enhanced.

DISCLOSURE OF THE INVENTION

As a result of studies, with the aim of solving the above-describedobjects, on the influence that Al composition, a crystal grain diameter,and so on in a Ti—Al alloy target give to a Ti—Al—N film, the inventorsof the present invention have found out that it is possible to enhancean epitaxial growth property of the Ti—Al—N film and to reduce dustgeneration when Al in an Ti—Al alloy is first solid-solubilized in Ti oris made to exist as an intermetallic compound with Ti to obtain auniform alloy structure (target structure).

It has been found out that especially the epitaxial growth property ofthe Ti—Al—N film is greatly enhanced by reducing variation in Al contentin the entire target. In other words, reduction in segregation of Alenhances the epitaxial growth property of the Ti—Al—N film. Meanwhile,it has been found out that the dust generation is greatly reduced byreducing variation in crystal grain diameter in the entire target.

The present invention is made based on the above findings. A firstsputter target of the present invention is a sputter target comprising aTi—Al alloy, characterized in that Al in the Ti—Al alloy exists in atleast one of a solid solution state in Ti and a state in which Al formsan intermetallic compound with Ti, and that variation in Al content inthe entire target is within 10%.

A second sputter target of the present invention is a sputter targetcomprising a Ti—Al alloy, characterized in that Al in the Ti—Al alloyexists in at least one of a solid solution state in Ti and a state inwhich Al forms an intermetallic compound with Ti, that an averagecrystal grain diameter of the Ti—Al alloy is 500 μm or smaller, and thatvariation in the crystal grain diameter in the entire target is within30%.

In the sputter target of the present invention, the Ti—Al alloypreferably contains Al in the range of 1 to 30 atm %.

A barrier film of the present invention is characterized in that itcomprises a Ti—Al—N film formed by using the sputter target of thepresent invention described above. The barrier film of the presentinvention is suitably used as a barrier material for a semiconductorsubstrate.

An electronic component of the present invention is characterized inthat it comprises the barrier film of the present invention describedabove. As a concrete form of the electronic component of the presentinvention, a semiconductor memory comprising a semiconductor substrate,the barrier film formed on the semiconductor substrate, and a thin-filmcapacitor formed on the barrier film can be named.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross sectional view showing a schematic structure of anelectronic component according to an embodiment of the presentinvention.

MODE FOR IMPLEMENTING THE INVENTION

An embodiment of the present invention will be hereinafter explained.

A sputter target of the present invention is made of a Ti—Al alloy, andis used for forming, for example, a Ti—Al—N film. Al in the Ti—Al alloyexists in a solid solution state in Ti or as an intermetallic compoundwith Ti. As the intermetallic compound of Ti and Al, TiAl, TiAl₃, TiAl₂,Ti₃Al, and the like can be named.

A uniform alloy structure is obtainable when Al is thus made to exist asa solid solution phase or an intermetallic compound phase. In otherwords, it is possible to make the sputter target structure a uniformsolid solution structure of Ti and Al, a uniform intermetallic compoundstructure of Ti and Al, or a uniform mixed structure of the solidsolution and the intermetallic compound. An epitaxial growth property ofthe Ti—Al—N film is enhanced by obtaining such a uniform targetstructure.

In contrast, when Al is precipitated as a single phase or segregation ofAl is caused in the Ti—Al alloy (sputter target), epitaxial growth ishindered. Al is solid-solubilized in Ti up to its solid solubilitylimit, and Al exceeding the solid solubility limit exists as theintermetallic compound with Ti, but it is highly possible that thesegregation of Al occurs depending on the Al composition and aproduction method. In the present invention, the precipitation andsegregation of Al are prevented.

It can be confirmed here by X-ray diffraction that Al in the Ti—Al alloytarget exists as the solid solution phase or the intermetallic compoundphase. More specifically, after a sample is taken from an arbitraryposition of the Ti—Al alloy target, the surface thereof is polished to#1000 and further subjected to buffing. A desired X-ray diffractionpattern of such a sample is such that only the peak of Ti and the peakof the Ti—Al intermetallic compound (TiAl, TiAl₃, TiAl₂, and the like)appear therein in effect. In other words, it is confirmed that Al existsas at least one of the solid solution phase and the intermetalliccompound phase if the peak of Al does not appear in effect.

Incidentally, it is defined that an effective peak in the X-raydiffraction pattern has an intensity ratio of 1/20 of the maximumintensity peak or higher. The X-ray diffraction is conducted under themeasurement conditions of X-ray: Cu, K-α1, voltage: 50 kV, electriccurrent: 100 mA, a vertical goniometer, a divergence slit: 1 deg, ascattering slit: 1 deg, a light-receiving slit: 0.15 mm, a scan mode:continuous, a scan speed: 5°/min, and a scan step: 0.05°.

The Ti—Al alloy constituting the sputter target of the present inventionpreferably contains Al in the range of 1 to 30 atm %. An Al content inthe Ti—Al alloy target exceeding 30 atm % increases the possibility thatAl which should be solid-solubilized in Ti or should form theintermetallic compound with Ti is precipitated as a single phase.Namely, the segregation of Al is easily caused. The precipitation of Alas a single phase lowers the epitaxial growth property of the Ti—Al—Nfilm when the Ti—Al—N film is formed by sputtering through the use ofthe Ti—Al alloy target. Moreover, the resistance and so on of theTi—Al—N film increase to degrade the characteristic as the barrier film.

By limiting the Al content in the Ti—Al alloy target to 30 atm % orsmaller, the target structure can be the uniform solid solutionstructure of Ti and Al, the uniform intermetallic compound structure ofTi and Al, or the uniform mixed structure of the solid solution and theintermetallic compound. Such a uniform target structure can also makethe resultant Ti—Al—N film structure a uniform solid solution structureof TiN and Al or a solid solution structure of TiN and AlN.

When the Al content in the Ti—Al alloy target is smaller than 1 atm %,however, the effect of enhancing oxidation resistance that it ought tohave is not fully obtainable. For example, oxidation easily progressesin the Ti—Al—N film formed by using the Ti—Al alloy target whose Alcomposition is lower than 1 atm % so that adherence to a film formedthereon is weakened, which easily causes peeling. For example, adherencebetween the Ti—Al—N film and a lower electrode of the thin-filmcapacitor is weakened.

Further, Al in the Ti—Al—N film not only enhances the oxidationresistance of the film itself but also functions as a trap material ofoxygen. For example, when an electrode film made of a conductive oxidesuch as SRO is formed on the Ti—Al—N film, the diffusion of oxygen inthis conductive oxide into a film-forming substrate such as asemiconductor substrate is restrained. From this point of view, it isalso preferable that the Al content in the Ti—Al alloy target is 1 atm %or higher.

An Al content (Al composition) of the Ti—Al alloy constituting thesputter target of the present invention is more preferably in the rangeof 1 to 20 atm % in order to restrain oxidation of the barrier filmitself more effectively and further enhance the epitaxial growthproperty of the resultant film. It is still more preferable that the Alcomposition is in the range of 5 to 15 atm %.

Further, in the sputter target of the present invention, variation inthe content of Al which is solid-solubilized in Ti or exists as theintermetallic compound with Ti is limited within 10% in the entiretarget. When the variation in the Al content in the entire target islimited to a low value, a smooth epitaxially grown film is obtainablewith good reproducibility. The variation in the Al content exceeding 10%causes a difference, for example, in a crystal growth property ofTi—Al—N due to a partial difference in the Al composition of theresultant film so that the epitaxial growth property as the entire filmis degraded. The variation in the Al content in the entire target ispreferably within 5%, more preferably within 1%.

Here, the variation in the Al content in the entire target is defined asa value derived in the following manner. Namely, when the target is in adisc shape, samples are taken from respective positions (totally 5positions including a center part), the respective positions being thecenter part of the target and positions 10% deviated from positions atwhich the periphery crosses two straight lines passing the center partand equally dividing the circumference, the Al content of each of thesefive samples is measured ten times, and an average value of the tenmeasured values is defined as the Al content of each of the samples.Then, the variation [%] defined in the present invention is calculatedfrom the maximum value and the minimum value of these measured valuesbased on an expression of {(maximum value−minimum value)/(maximumvalue+minimum value)}×100. A value measured by inductively coupledplasma emission spectroscopy in general use is used as the Al content.

The sputter target of the present invention is preferably constituted ofa high-purity Ti—Al alloy. Since especially oxygen among impuritiesincluded in the Ti—Al alloy degrades the epitaxial growth property ofthe resultant Ti—Al—N film, an average oxygen content of the Ti—Al alloyis preferably 900 ppm or lower. Further, oxygen promotes oxidation ofthe resultant Ti—Al—N film to lower adherence of a film (for example thelower electrode of the thin-film capacitor) formed thereon. Also fromthis point of view, the average oxygen content of the Ti—Al alloy ispreferably limited to 900 ppm or lower.

Complete removal of oxygen from the Ti—Al alloy target, however, maypossibly degrade a barrier property of the resultant Ti—Al—N film, andtherefore, the Ti—Al alloy target preferably contains a minute amount ofoxygen. Specifically, the Ti—Al alloy target preferably contains oxygenin the range of 10 to 500 ppm. The oxygen content is more preferably inthe range of 50 to 400 ppm. Such an amount of oxygen effectivelyfunctions for the barrier property of the Ti—Al—N film.

Variation in the oxygen content in the Ti—Al alloy target is preferablywithin 30% as the entire target. When the variation in the oxygencontent in the entire target is limited to a low value, the epitaxialgrowth property, the oxidation resistance, and so on of the Ti—Al—N filmformed by using it can be enhanced over the entire film with goodreproducibility. Moreover, the barrier property of the resultant Ti—Al—Nfilm can be made uniform. The variation in the oxygen content in theentire target is calculated in the same manner as that for the aforesaidvariation in the Al content. A value measured by an inert gasfusion-infrared absorption method in general use is used as the oxygencontent.

Incidentally, the sputter target of the present invention (the Ti—Alalloy target) may contain some amount of impurity elements other thanoxygen if the level of its content is about the same as that in ageneral high-purity metal material. It is also preferable, however, thatan content of other impurity elements is reduced similarly to the oxygencontent in order to realize the enhancement in the epitaxial growthproperty and so on.

In the sputter target of the present invention, an average graindiameter of crystal grains (average crystal grain diameter) constitutingthe Ti—Al alloy is preferably 500 μm or smaller. Further, variation inthe crystal grain diameter in the entire target is preferably within30%. When the crystal grains constituting the Ti—Al alloy target aremade relatively microscopic and the variation in the crystal graindiameter in the entire target is reduced, dust generation can bereduced.

There are many reports on the correlation between the crystal graindiameter of the target and the dust. What is called dust generallyincludes flaky substances which are generated when grains scattered bysputtering, after adhering to an adhesion preventive board disposed in asputtering device and a non-erosion region of the target, peel off theseplaces, and molten grains called splashes which are generated due toabnormal discharge caused by a potential difference occurring in a gapamong crystal grains. In any case, it generally means the abovesubstances which are approximately 0.2 to 0.30 μm in size.

In contrast, the dust generated suddenly from the conventional Ti—Alalloy target is 1 μm or larger in size, which is relatively largecompared with the dust described above. Further, it is in a rock-likemassive shape. This massive dust is in such a mode in which a part ofthe crystal grains or the crystal grains themselves are extracted by thesputtering. When the variation in the crystal grain diameter in theentire target exists, the occurrence rate of such a huge dust increases.

On the other hand, when the average crystal grain diameter of the Ti—Alalloy target is limited to 500 μm or smaller and the variation in thecrystal grain diameter in the entire target is limited within 30%, itbecomes possible to reduce the scattering of a part of the crystalgrains or the crystal grains themselves which is caused by the influenceof thermal stress or the like. As a result, the generation of the hugedust can be reduced and the yields of the Ti—Al—N film can be greatlyenhanced.

The crystal grain diameter of the Ti—Al alloy target is more preferably300 μm or smaller, still more preferably 200 μm or smaller. Further, thevariation in the crystal grain diameter in the entire target is morepreferably within 15%, still more preferably within 10%. Incidentally,as is previously described, the uniform solid solution structure inwhich Al is solid-solubilized in Ti and the uniform intermetalliccompound structure of Ti and Al also work effectively for the reductionof the huge dust.

Here, the average crystal grain diameter of the Ti—Al alloy target isdefined as a value derived in the following manner. First, samples aretaken from the surface of the sputter target, the surfaces of thesamples are etched with an etching solution in which HF:HNO₃:H₂O=2:2:1,and thereafter, structure observation is conducted with an opticalmicroscope. A circle with a predetermined area (diameter 79.8 mm) isdepicted on a field of view for measurement or on a picture of theoptical microscope, and the number of the crystal grains completelyembraced in the circle (number A) and the number of the crystal grainscut off by the periphery (number B) are counted. The magnification ofthe measurement is so set that the number of the crystal grainscompletely embraced in the circle is 30 or larger. The total number n ofthe crystal grains in the circle is defined as a value of the numberA+the number B/2 in which the number B of the crystal grains isconverted to ½. An average crystal grain diameter d (mm) is calculatedfrom this total number n of the crystal grains in the circle, themeasurement magnification M, and an area A (mm²) of the circle based onthe following expression.

d=(A/n)^(1/2) /M

In order to calculate the variation in the crystal grain diameter in theentire target, samples are taken from respective positions (totally ninepositions including a center part), the respective positions being thecenter part of the target, positions near positions at which theperiphery crosses the two straight lines passing the center part andequally dividing the circumference, and positions as half distant fromthe periphery as the above positions, an average crystal grain diameterof each of the nine samples is measured ten times in the aforesaidmethod, and the average value of the ten measured values is defined asthe crystal grain diameter of each of the samples. Then, the variation[%] of the crystal grain diameter defined in the present invention iscalculated from the maximum value and the minimum value of thesemeasured values based on the expression of {(maximum value−minimumvalue)/(maximum value+minimum value)}×100. Note that the shape of thesample is 10 mm in length and 10 mm in width.

The sputter target of the present invention is preferably produced byapplying melting methods as described below, though a production methodthereof is not specially limited to the following methods, and further,it is preferable that the variation in the Al content is reduced bycontrolling various conditions of each of the melting methods.

Ti and Al whose purity is as high as approximately 4N are preparedfirst, and they are melted by an arc melting method, an electron beam(EB) melting method, a cold wall melting method, or the like to producea Ti—Al alloy ingot. Especially, the cold wall melting method ispreferably employed among these melting methods. The cold wall meltingmethod, when the melting conditions thereof are controlled, enables toobtain, with good reproducibility, a uniform alloy structure in whichthe segregation of Al is reduced. The cold wall melting method is alsoeffective in reducing the impurity elements and reducing the variationtherein.

As concrete conditions in employing the cold wall melting method, thepressure before the start of the melting is first set to approximately1×10⁻⁶ Pa (1×10⁻⁴ to 1×10⁻⁷ Pa), and degassing (baking) is carried outabout twice before the melting. The pressure at the start of the meltingis set to approximately 1×10⁻⁵ Pa (1×10⁻⁴ to 1×10⁻⁶ Pa), and thepressure while the melting is carried out is set to approximately 1×10⁻⁴Pa (1×10⁻³ to 1×10⁻⁵ Pa). Power supply at the start of the melting isset to approximately 5 kW, and the maximum pressure while the melting iscarried out is set to approximately 230 kW. Melting time is preferablyset to approximately 40 minutes.

It is preferable to further carry out solution treatment at atemperature in the range of 80 to 90% of a melting point of the Ti—Alalloy after the cold wall melting is carried out in order to reduce thevariation in the Al content. The solution treatment is preferablycarried out in a vacuum at 1×10⁻¹ Pa or lower or an Ar atmosphere for 24hours or longer. Such solution treatment is effective not only forreducing the variation in the Al content but also for reducing thevariation in the oxygen content and miniaturizing and uniformizing thecrystal grain diameter.

When the solution treatment temperature is too high here, the crystalgrains grow rapidly to be liable to crack. On the other hand, when thesolution treatment temperature is too low, sufficient dispersion effectof Al is not obtainable. In view of the above, the solution treatmenttemperature is preferably in the range of 80 to 90% of the melting pointof the Ti—Al alloy. It is more preferably in the range of 85 to 90% ofthe melting point. Further, since an insufficient degree of vacuum atthe time of the solution treatment tends to cause oxidation of the Ti—Alalloy, the pressure at this time should be at 1×10⁻¹ Pa or lower.Further, when the solution treatment time is too short, the dispersioneffect of Al becomes insufficient, and therefore, the solution treatmenttime is preferably 24 hours or longer.

Incidentally, since the arc melting method and the EB melting method arehighly possible to cause the segregation of Al, it is preferable tocarry out the melting a plurality of times (for example, twice to threetimes). The arc melting and the EB melting thus carried out a pluralityof times can reduce the segregation of Al.

Next, the resultant ingot undergoes a plastic work such as forging androlling when necessary. The working ratio at this time is, for example,60 to 95%. Such a plastic work can give an appropriate amount of thermalenergy to the ingot and the energy enables the uniformization of Al andoxygen. When the working ratio is too high, cracks tend to occur at thetime it is worked. On the other hand, when the working ratio is too low,recrystallization in a later process becomes insufficient. In view ofthis, the working ratio at the time of the plastic work is preferably inthe range of 60 to 95%. The working ratio is more preferably in therange of 70 to 90%, still more preferably in the range of 80 to 90%.

Thereafter, the Ti—Al alloy material is annealed at the temperature of900 to 1200° C. to be recrystallized. The average crystal grain diameterand the variation therein can be controlled to be in the rangeprescribed in the present invention by the adjustment of conditions forthe recrystallization. When the annealing temperature is too high, thegrain diameter of the recrystallized grains becomes too large. On theother hand, when the annealing temperature is too low, therecrystallization becomes insufficient. Accordingly, the annealingtemperature is preferably in the range of 900 to 1200° C. The annealingtemperature is more preferably in the range of 950 to 1150° C., stillmore preferably in the range of 1000 to 1100° C.

A target material made of the Ti—Al alloy obtained by theabove-described melting method is machined into a desired target shapeand bonded to a backing plate made of, for example, Al and Cu so thatthe aimed sputter target is obtainable. In bonding it to the backingplate, diffusion bonding or brazing bonding using at least one of In,Zn, and Sn or using a brazing filler metal containing them is adoptable.Alternatively, instead of using the separate backing plate, abacking-plate shape may be formed at the same time when the sputtertarget is produced to form an integral-type sputter target.

The barrier film of the present invention comprises the Ti—Al—N film(Ti_(1-x)Al_(x)N film (0.01≦x≦0.3)) which is formed by reactivesputtering with mixed gas of, for example, Ar and N₂, using theabove-described sputter target (Ti—Al alloy target) of the presentinvention. The Ti—Al—N film thus obtained is excellent in the expitaxialgrowth property on the semiconductor substrate such as the Si substrateand has a good characteristic as the barrier film, and the dustgeneration is greatly reduced therein. The use of the Ti—Al alloy targetof the present invention makes it possible to obtain the barrier film(Ti—Al—N film) excellent in its characteristic and quality with goodyields.

The Ti—Al—N film of the present invention is excellent in a barrierproperty against various kinds of elements such as, for example, Sr andBa, and has a low resistance, resistivity thereof being 200 μΩ·cm orlower. Therefore, the use of such a Ti—Al—N film as the barrier filmbetween the semiconductor substrate and various kinds of elements canwell reduce mutual diffusion between the semiconductor substrate and anelement configuration layer. Further, oxidation of the Ti—Al—N film dueto the high temperature annealing (for example, 600° C. or higher) canbe prevented so that degradation in adherence on the interface betweenthe Ti—Al—N film and the element configuration layer can be prevented.In other words, peeling-off or the like of the element configurationlayer on the Ti—Al—N film can be prevented. Further, improvement in thecharacteristic of the element configuration layer is realized since theepitaxial growth of the element configuration layer is not hindered.

The above-described Ti—Al—N film is suitable as the barrier material forthe semiconductor substrate. The barrier film of the present inventiondescribed above is applicable to various kinds of electronic components.More specifically, the barrier film of the present invention iseffectively used for a semiconductor memory such as FRAM and DRAM inwhich a semiconductor substrate with a switching transistor formedthereon and a thin-film capacitor (memory cell) using a dielectric thinfilm made of a perovskite oxide are combined.

FIG. 1 is a cross sectional view schematically showing a capacitorportion of a semiconductor memory as an embodiment of an electroniccomponent of the present invention. In the drawing, 1 denotes asemiconductor substrate (Si substrate), though not illustrated, on whicha switching transistor is formed. The Ti—Al—N film (Ti_(1-x)Al_(x)N film(0.01≦x≦0.3)) of the present invention described above is formed as abarrier film 2 on this semiconductor substrate 1, and a thin-filmcapacitor 3 is further formed thereon.

The thin-film capacitor 3 has a lower electrode 4, a dielectric thinfilm 5, and an upper electrode 6 which are formed in sequence on thebarrier film 2. For the lower electrode 4, used is a noble metal such asPt, Au, Pd, Ir, Rh, Re, and Ru, and an alloy thereof (Pt—Rh, Pt—Ru, andthe like), or a conductive perovskite oxide such as SrRuO₃, CaRuO₃,BaRuO₃ and a solid solution thereof (for example, (Ba, Sr)RuO₃ and (Sr,Ca)RuO₃), or the like. A noble metal (including an alloy), a conductiveperovskite oxide, or the like similar to that used for the lowerelectrode 4 is preferably used as a constituting material of the upperelectrode 6, though not specifically limited thereto.

A dielectric material having a perovskite crystal structure is suitablefor the dielectric thin film 5. As such a dielectric material, aperovskite oxide expressed as ABO₃ can be named. Especially, preferablyused is a perovskite oxide (BSTO or the like) in which barium titanate(BaTiO₃ (BTO)) is a major component thereof, and a part of an A-siteelement (Ba) thereof is substituted by an element such as Sr and Ca or apart of a B-site element (Ti) thereof is substituted by an element suchas Zr, Hf and Sn.

The perovskite oxide with BTO being the major component thereof becomesa ferroelectric substance or a paralectric substance depending on thesubstitution amount of the B-site element and the A-site element, andthe distortion amount based on lattice distortion. Therefore, when thecomposition and the distortion amount of the perovskite oxide areappropriately set, the dielectric thin film 5 suitable for the intendeduse of the thin capacitor 3 is obtainable. For example,Ba_(a)Sr_(1-a)TiO₃ (BSTO) exhibits a ferroelectric property when a molefraction a of Ba is in the range of 0.3 to 1. Meanwhile, when the molefraction a of Ba is in the range of 0 to 0.3, it exhibits a paraelectricproperty. These properties also vary depending on the substitutionamount of the B-site element.

Incidentally, for the dielectric thin film 5, aperovskite oxide otherthan BTO and BSTO is also applicable, for example, a simple perovskiteoxide such as SrTiO₃, CaTiO₃, BaSnO₃, and BaZrO₃, a complex perovskiteoxide such as Ba(Mg_(1/3)Nb_(2/3))O₃ and Ba(Mg_(1/3)Ta_(2/3))O₃, andsolid solution thereof. Some degree of difference in the composition ofthe perovskite oxide from stoichiometry is of course tolerable.

In the above-described semiconductor memory, the barrier film 2 made ofthe Ti—Al—N film excellent in the barrier property and oxidationresistance makes it possible to suitably form the thin-film capacitor 3on the semiconductor substrate 1 without degrading the characteristicthereof. Especially, the lower electrode 4 of the thin-film capacitor 3is sufficiently prevented from peeling off the barrier film 2. The filmthickness of the barrier layer 2 is preferably small in such a range asto allow the diffusion preventive effect to be obtainable, and to beconcrete, it is preferably in the range of 10 to 50 nm.

The Ti—Al—N film as the barrier film 2, which is an epitaxially grownfilm, promotes the epitaxial growth of the lower electrode 4 and thedielectric thin film 5 thereon so that it becomes possible to producethe thin-film capacitor with a suitable film thickness on thesemiconductor substrate 1, the thin-film capacitor utilizing aferroelectric property and a highly dielectric property which areinduced, for example, by the distortion introduced at the time of theepitaxial growth. Consequently, a high degree of integration of suchthin-film capacitors and transistors on the semiconductor substrateenables the production, with high yields, of a highly practical andhighly reliable semiconductor memory such as FRAM and DRAM.

Next, concrete embodiments of the present invention will be explained.

Embodiment 1

High-purity Ti and Al pieces were melted by the cold wall melting methodto produce alloy ingots (diameter 105 mm) whose Al contents were asshown in Table 1 respectively. In a cold wall melting process, thepressure before the start of the melting was set to 1×10⁻⁶ Pa anddegassing (baking) was carried out twice before the melting. Thepressure was adjusted to 1×10⁻⁵ Pa at the start of the melting and thepressure while the melting was carried out was set to 1×10⁻⁴ Pa. Powersupply at the start of the melting was set to 5 kW and the maximumpressure while the melting was carried out was set to 230 kW. Meltingtime was set to 40 minutes. Each of the alloy ingots obtained by suchcold wall melting was subjected to solution treatment at the temperatureand time shown in Table 1.

Next, each of the above alloy ingots was subjected to hot rolling at1000° C. at the working ratio shown in Table 1, and thereafter, wasannealed at 900° C. for one hour for recrystallization. Each of thealloy materials after the recrystallization was ground and polished, wasthereafter diffusion-bonded to a backing plate made of Al by hotpressing, and further subjected to machining, thereby producing each ofTi—Al alloy targets with the diameter 320 mm×thickness 10 mm.

As a result of X-ray diffraction of each of the Ti—Al alloy targets thusobtained, it was confirmed that only a Ti peak and a Ti—Al intermetalliccompound peak appeared in any one of X-ray diffraction patterns. Inother words, each of the Ti—Al alloy targets had a uniform structureconstituted of a Ti—Al solid solution structure and a Ti—Alintermetallic compound structure. Variation in the Al content, anaverage oxygen content, and variation in the oxygen content of each ofthe Ti—Al alloy targets were further measured according to the aforesaidmethod. The measured results are shown in Table 1.

TABLE 1 Hot- Solution work- Al treatment ing con- Oxy- Oxy- Tem- work-Al tent gen gen Sam- Melt- per- ing con- vari- con- vari- ple ing ature*Time ratio tent ation tent ation No. method (%) (h) (%) (at %) (%) (ppm)(%) EM- 1 Cold 90 30 95 3 2 600 12 BODI- 2 wall 90 24 80 3 4 430 8 MENT3 melt- 85 24 80 3 6 510 20 1 4 ing 85 24 65 3 7 670 34 5 method 80 2465 3 10 260 10 6 90 40 92 9 1 380 18 7 90 40 60 9 3 450 8 8 85 35 60 9 5250 10 9 80 30 60 9 7 780 22 10 80 24 60 9 10 590 20 11 90 48 60 16 2350 30 12 85 40 60 16 5 140 16 13 80 35 60 16 7 220 24 14 80 30 60 16 8410 18 15 80 24 60 16 10 1070 10 *: Ratio to the melting point of theTi-Al alloy

Embodiment 2

High-purity Ti and Al pieces were melted by the arc melting method toproduce alloy ingots (diameter 105 mm) whose Al contents were as shownin Table 2 respectively. The arc melting was carried out with 150 kWoutput after vaccumizing is first carried out up to 6.65×10⁻³ Pa and Arwas introduced up to 1.9×10⁴ Pa. The number of times the arc melting wascarried out for each is as shown in Table 2. Next, each of the alloyingots obtained by the arc melting was subjected to solution treatmentat the temperature shown in Table 2 for 30 hours. These alloy materialswere hot-rolled at 1000° C., and thereafter, each of Ti—Al alloy targetswith the diameter 320 mm×thickness 10 mm was produced, similarly to theEmbodiment 1.

As a result of X-ray diffraction of each of the Ti—Al alloy targets thusobtained, it was confirmed that only a Ti peak and a Ti—Al intermetalliccompound peak appeared in any one of X-ray diffraction patterns. Inother words, each of the Ti—Al alloy targets had a uniform structureconstituted of a Ti—Al solid solution structure and a Ti—Alintermetallic compound structure. Variation in the Al content, anaverage oxygen content, and variation in the oxygen content of each ofthe Ti—Al alloy targets were further measured according to the aforesaidmethod. The measured results are shown in Table 2.

TABLE 2 Solu- tion treat- Al ment Al con- Oxy- Oxy Melting Tem- con-tent gen gen Sam- Melt- No. per- tent vari- con- vari- ple ing of ature*(at ation tent ation No. method times (%) %) (%) (ppm) (%) EM- 1 Arc 390 4 3 350 11 BODI- 2 melt- 2 80 4 5 530 8 MENT 3 ing 2 85 4 6 640 14 24 method 2 80 4 8 420 18 5 2 80 4 10 270 16 6 3 90 7 2 160 5 7 3 80 7 3290 4 8 2 90 7 6 740 20 9 2 85 7 7 860 26 10 2 85 7 9 530 12 11 4 80 181 380 22 12 3 80 18 4 320 19 13 3 85 18 5 480 37 14 2 85 18 7 990 10 152 90 18 8 940 13 *: Ratio to the melting point of the Ti-Al alloy

Embodiment 3

High-purity Ti and Al pieces were melted (degree of vacuum 1.33×10³ Pa,output 80 kW) by the EB melting method to produce alloy ingots (diameter105 mm) whose Al contents were as shown in Table 3 respectively. Thenumber of times the EB melting was carried out is as shown in Table 3.Next, each of the alloy ingots obtained by the EB melting was subjectedto solution treatment at the temperature shown in Table 3 for 30 hours.These alloy materials were hot-rolled at 1000° C., and thereafter, eachof Ti—Al alloy targets with the diameter 320 mm×thickness 10 mm wasproduced, similarly to the Embodiment 1.

As a result of X-ray diffraction of each of the Ti—Al alloy targets thusobtained, it was confirmed that only a Ti peak and a Ti—Al intermetalliccompound peak appeared in any one of X-ray diffraction patterns. Inother words, each of the Ti—Al alloy targets had a uniform structureconstituted of a Ti—Al solid solution structure and a Ti—Alintermetallic compound structure. Variation in the Al content, anaverage oxygen content, and variation in the oxygen content of each ofthe Ti—Al alloy targets were further measured according to the aforesaidmethod. The measured results are shown in Table 3.

TABLE 3 Solu- tion treat- Al ment Al con- Oxy- Oxy- Melting Tem- con-tent gen gen Sam- Melt- No. per- tent vari- con- vari- ple ing of ature*(at ation tent ation No. method times (%) %) (%) (ppm) (%) E 1 EB 3 90 93 420 9 3 2 melt- 3 85 9 4 370 14 3 ing 2 80 9 6 560 6 4 method 2 80 9 7840 18 5 2 90 9 9 920 22 *: Ratio to the melting point of the Ti-Alalloy E3 = Embodiment 3

COMPARATIVE EXAMPLES 1 TO 4

As Comparative Example 1 with the present invention, a Ti—Al alloytarget was prepared in the same manner as in Embodiment 1 except that acompacted and sintered Ti—Al alloy material (sintered compact) was used.As Comparative Example 2 and Comparative Example 3, Ti—Al alloy targetswere prepared in the same manner as that for the sample No. 13 ofEmbodiment 2 and the sample No. 3 of Embodiment 3 respectively exceptthat the arc melting or the EB melting was carried out oncerespectively.

Further, as Comparative Example 4, a Ti—Al alloy target was prepared inthe same manner as that for the sample No. 9 of Embodiment 1 except thatthe solution treatment was not carried out in the cold wall method.Variation in the Al content, an average oxygen content, and variation inthe oxygen content of each of the Ti—Al alloy targets in ComparativeExamples 1 to 4 were measured according to the aforesaid method. Themeasured results are shown in Table 4.

TABLE 4 Al Oxygen Al content Oxygen content Melting content variationcontent variation method (aat %) (%) (ppm) (%) Comparative (sintering 153 4800 35 Example 1 method) Comparative Arc Example 2 melting 15 13 60014 method (once) Comparative EB Example 3 melting 15 22 600 15 method(once) Comparative Cold Example 4 wall 9 18 690 22 method

Next, Ti—Al—N films were formed on Si(100) substrates to beapproximately 10 to 100 nm in thickness by reactive sputtering, usingthe Ti—Al alloy targets of the examples 1 to 3 and the comparativeexamples 1 to 3 described above. Mixed gas of N₂ and Ar (N₂=3 sccm,Ar=30 sccm) was used as sputtering gas, and substrate temperature wasset to 600° C. As each of the Si(100) substrates, a substratesurface-etched with a 1% HF solution for three minutes and rinsed offwith ultra pure water for 30 minutes was used. The number of the Sisubstrates on which the Ti—Al—N films were formed was 500 respectively.

Crystallinity of each of the Ti—Al—N films thus formed was confirmed byRHEED (Reflection High Energy Electron Diffraction) provided in a vacuumchamber. In other words, judgment was made from diffraction patterns ofRHEED on whether or not it was an epitaxial film. It was observed foreach of the 500 Si substrates used for the film forming in each of theexamples whether or not each of the Ti—Al—N films was epitaxially grown.The results are summarized in Table 5. The values in Table 5 indicatethe number of the epitaxially grown films among the 500 films inpercentage (%).

Next, using each of the above-described Ti—Al—N films as a barrier film,a Pt film is formed thereon by RF magnetron sputtering (substratetemperature 500° C.) to be a lower electrode. The thickness of the Ptfilm was approximately 100 nm. A BaTiO₃ film (approximately 200 nm infilm thickness) was further formed thereon as a dielectric film by theRF magnetron sputtering. At this time, substrate temperature was set to600° C. and 100% O₂ was used as sputtering gas.

Observation on whether or not each of the BaTiO₃ films was epitaxiallygrown was made in the same manner as in the observation on the Ti—Al—Nfilm. The results are also shown in Table 5. The values in Table 5indicate the number of the epitaxially grown films among the 500 filmsin percentage (%). Further, a Pt film was formed as an upper electrodeat room temperature by the RF magnetron sputtering using lift-off,thereby producing a thin-film capacitor for FRAM.

TABLE 5 Evaluation result of Evaluation result of epitaxial growthepitaxial growth Sample property property No. of Ti-Al-N film (%) of BTOfilm (%) Embodi- 1 98 98 ment 1 2 97 95 3 96 96 4 94 94 5 90 90 6 95 957 99 98 8 94 93 9 92 91 10 91 90 11 98 97 12 96 94 13 93 92 14 91 91 1590 90 Embodi- 1 97 96 ment 2 2 94 93 3 93 92 4 91 90 5 91 90 6 99 97 798 97 8 94 93 9 92 92 10 91 90 11 97 96 12 92 91 13 93 92 14 91 90 15 9090 Embodi- 1 96 95 ment 3 2 95 95 3 94 93 4 92 92 5 90 90 Comparative 5550 Example 1 Comparative 90 69 Example 2 Comparative 74 53 Example 3Comparative 81 72 Example 4

As is apparent from Table 5, all of the Ti—Al—N films formed by usingthe respective sputter targets according to the examples 1 to 3 areexcellent in the epitaxial growth property, and in accordance with this,enable good epitaxial growth of the BaTiO₃ films. Further, it wasconfirmed that all of the BaTiO₃ films according to the Embodiments 1 to3 have good remanent polarization.

Embodiment 4

High-purity Ti and Al pieces were melted by the cold wall melting methodto prepare a plurality of alloy ingots (75 to 105 mm in diameter) whoseAl content was 9 atm %. Next, these alloy ingots were subjected to hotrolling (a working ratio 80%) at 1000° C., and thereafter, were annealedfor one hour at the temperature shown in Table 2 respectively forrecrystallization.

After these alloy ingots were ground and polished, they arediffusion-bonded to backing plates made of Al by hot pressingrespectively and were further subjected to machining, thereby preparingTi—Al alloy targets with the diameter 320 mm×thickness 10 mm.

An average crystal grain diameter of each of the Ti—Al alloy target thusobtained and variation therein were measured according to the aforesaidmethod. The measured results are shown in Table 6. Incidentally, each ofthe Ti—Al alloy targets had a uniform structure constituted of a Ti—Alsolid solution structure and a Ti—Al intermetallic compound structuresimilarly to Embodiment 1. Further, variation in the Al content was alsosimilar to Embodiment 1.

Ti—Al—N films were formed on Si(100) substrates to be approximately 10to 100 nm in thickness by reactive sputtering, using the above-describedTi—Al alloy targets respectively. The film forming conditions of theTi—Al—N films were as described above. The number of the Si substrateswas 500 respectively.

The number of dusts having the size of 1 μm or larger among dustsexisting in each of the Ti—Al—N films thus obtained was measured with aparticle counter. The results are also shown in Table 6. The number ofthe dusts in Table 6 is an average value among 500 films. Incidentally,when crystallinity of each of the films was confirmed by RHEED providedin a vacuum chamber, it was a diffraction pattern of an epitaxial filmand a streak was observed, thereby confirming that a smooth epitaxialfilm was formed.

TABLE 6 Ti-Al alloy target Average Average Crystal number of dustThermal crystal grain [1 μm or larger Sam- treatment grain diameter insize] ple temperature diameter variation (number/ No. (° C.) (μm) (%)piece) Embodi- 1 900 140 11 3.8 ment 2 1000 130 23 7.8 4 3 1050 220 97.2 Compara- 1 750 120 42 47.8 tive 2 1200 640 22 39.1 Exmple 5 3 1300730 37 53.6

As is apparent from Table 6, only a small number of dusts are includedin all of the Ti—Al—N films formed by using the respective sputtertargets according to the example 4. Therefore, the use of such a Ti—Al—Nfilm as a barrier film can improve production yields of various kinds ofdevices.

INDUSTRIAL APPLICABILITY

As is apparent from the above-described embodiment, according to thesputter target of the present invention, it is made possible to form aTi—Al—N film or the like excellent in the characteristic and quality asa barrier film with good reproducibility. Therefore, the use of abarrier film made of such a Ti—Al—N film can realize improvement in thecharacteristic and yields of various kinds of electronic components. Thebarrier film of the present invention is especially suitable for FRAMand DRAM using a perovskite oxide film as a dielectric film.

What is claimed is:
 1. A sputter target for forming an epitaxial grownbarrier film, the sputter target comprising a Ti—Al alloy containing 1to 30 atomic % of Al wherein Al in said Ti—Al alloy exists in at leastone of a solid solution state in Ti and a state in which Al forms anintermetallic compound with Ti, and variation in Al content in theentire target is within 10%, wherein the variation of the Al content isdefined according to the following expression: variation (%)={(maximumvalue−minimum value)/(maximum value+minimum value)×100.
 2. The sputtertarget according to claim 1, wherein said Ti—Al alloy has an averagecrystal grain diameter equal to 500 μm or less.
 3. The sputter targetaccording to claim 2, wherein variation in crystal grain diameter in theentire target is within 30%.
 4. The sputter target according to claim 1,wherein an average oxygen content of said Ti—Al alloy is 900 ppm orless.
 5. The sputter target according to claim 4, wherein variation inthe oxygen content in the entire target is within 30%.
 6. The sputtertarget according to claim 1, wherein said sputter target is bonded to abacking plate.
 7. A sputter target for forming an epitaxial growthbarrier film, said sputter target comprising a Ti—Al alloy whose Alcontent is in a range of 1 to 30 atm %, wherein Al in said Ti—Al alloyexists in at least one of a solid solution state in Ti and a state inwhich Al forms an intermetallic compound with Ti, an average crystalgrain diameter of said Ti—Al alloy is 500 μm or smaller, and variationin crystal grain diameter in the entire target is within 30% wherein thevariation of the crystal grain diameter is defined according to thefollowing expression: variation (%)={(maximum value−minimumvalue)/(maximum value+minimum value)×100.
 8. The sputter targetaccording to claim 7, wherein said sputter target is bonded to a backingplate.
 9. A barrier film comprising a Ti—Al—N film formed by using thesputter target according to claim 1, wherein said barrier film is anepitaxially grown film having a thickness in a range of 10 to 100 nm.10. The barrier film according to claim 9, wherein said Ti—Al—N film isused as a barrier material for a semiconductor substrate.
 11. A barrierfilm comprising a Ti—Al—N film formed by using the sputter targetaccording to claim 7, wherein said barrier film is an epitaxially grownfilm having a thickness in a range of 10 to 100 nm.
 12. The barrier filmaccording to claim 11, wherein said Ti—Al—N film is used as a barriermaterial for a semiconductor substrate.
 13. An electronic componentcomprising the barrier film according to claim
 9. 14. The electroniccomponent according to claim 13, comprising: a semiconductor substrate,said barrier film epitaxially formed on said semiconductor substrate,and a thin-film capacitor which is epitaxially formed on said barrierfilm.
 15. An electronic component comprising the barrier film accordingto claim
 11. 16. The electronic component according to claim 15,comprising: a semiconductor substrate, said barrier film epitaxiallyformed on said semiconductor substrate, and a thin-film capacitorepitaxially formed on said barrier film.
 17. The sputter targetaccording to claim 1, wherein the variation of the Al content is within5% or less.
 18. The sputter target according to claim 7, wherein thecrystal grain diameter of the Ti—Al alloy target is 300 μm or smaller.